buildings Review The Sustainability of Tall Building Developments: A Conceptual Framework Kheir Al-Kodmany Department of Urban Planning and Policy, College of Urban Planning and Public Affairs, University of Illinois at Chicago, Chicago, IL 60612, USA; [email protected] Received: 26 November 2017; Accepted: 3 January 2018; Published: 5 January 2018 Abstract: As cities cope with rapid population growth—adding 2.5 billion dwellers by 2050—and grapple with expansive sprawl, politicians, planners, and architects have become increasingly interested in the vertical city paradigm. This paper reviews and examines shortfalls of tall buildings found in the literature to inform future developments. The paper gathers a vast amount of fragmented criticism and concerns, and organizes them around the three pillars of sustainability: social, economic, and environmental. Mapping out the “unsustainable” aspects forms the foundation for addressing them in future research and tall building developments. Keywords: sustainability; high-rise developments; economic shortfalls; social failure; environmental problems 1. Introduction 1.1. What Is a Tall Building? There is no universally accepted definition of a “tall building”. Governments around the world differ in how they define “tall buildings”. For example, German regulations define “tall buildings” as buildings higher than 22 m (72 ft) with room for the permanent accommodation of people [1]. City officials derived this limit from the length of ladders used by the firefighters. Leicester City Council in the UK defines a tall building as any structure over 20 m/66 ft in height, and/or a building of any height that is substantially higher than the predominant height of the buildings in the surrounding area, and/or a building that would make a significant impact on the city’s skyline [2]. In Ireland, Cork City defines tall buildings as buildings of 10 stories and higher [3]. The ASHRAE (American Society of Heating, Refrigerating, and Air-conditioning Engineers) Technical Committee for Tall Buildings defines them as buildings higher than 91 m/300 ft [4]. A similar definition problem is found when we search for definitions of a high-rise building, a tower, or a skyscraper. However, in most cases, differences in definitions are insignificant for this research. For the sake of simplicity, brevity, and based on research by the Council on Tall Buildings and Urban Habitat (CTBUH), the Emporis, and others [5–9], this paper embraces the following definitions: • A tall building, a high-rise, or a tower is a 50 m+ (164 ft+) building. • A skyscraper is a 150 m+ (328 ft+) building. • A supertall or ultra-tall is a 300 m+ (984 ft+) building. • A megatall is a 600 m+ (1967 ft+) building. 1.2. The Tall Building Construction Boom Since 1990, most cities have seen a steady increase in urban dwellers. In 1990, 43 percent of the world’s population (2.3 b/5.4 b) lived in urban areas, and by 2015, this had grown to 54 percent (4.0 b/7.4 b). By 2030, the United Nations expects that 60 percent of the world’s population (5.1 b/8.5 b) Buildings 2018, 8, 7; doi:10.3390/buildings8010007 www.mdpi.com/journal/buildings Buildings 2018, 8, 7 2 of 31 will live in urban areas; and in 2050, 80 percent of the world’s population (7.7 b/9.7 b) will live in urban areas. At the time of this writing (2017), the urban population constitutes about 55 percent of the world’s population (4.1 b/7.5 b). Therefore, by 2050, urban population will increase about 2.5 billion people. That is, the projected urban population increase is 80 million people a year. This is equivalent to about 1.5 million new urban dwellers a week or 220 thousand a day. Geographically, this would be the equivalent of building eight mega cities (defined as cities with 10 million people and greater) a year. By 2050, in addition to having a greater number of mega cities, currently existing mega cities of the world, particularly those in Asia, Africa, and Latin America will house greater populations, ranging from 30 to 50 million people or more [10]. Although tall buildings are not the only way to accommodate the increasing urban population—it is possible to do so with mid-rise buildings—cities are constructing tall buildings across the globe rapidly (p. 9 [10]). Indeed, since 2000, cities have constructed more tall buildings than it did in the previous 115 years—Year 1885 is considered the birth date of skyscrapers [10]. These new buildings are also reaching record-breaking heights. For example, before the year 2000, we constructed only 24 supertalls. Since that time, over 84 supertalls have been completed. Further, from 1930 to 2001, the world has completed 282 200 m+ buildings (an average of about four buildings per year), while from 2002 to 2015, that number was 679 (an average of 52 buildings per year). In the past decade, a new height category was created for skyscrapers known as “megatalls” that are over 600 m (1979 ft) tall. Three megatalls have already been constructed, and several more are currently under construction. In recent years, the “super mega-tall”, category has arrived as buildings such as the 1000 m+ Jeddah Tower in Saudi Arabia are built [11]. The driving forces for building tall include massive migration from rural to urban areas, rapid urban renewal, skyrocketing land prices, active agglomeration, globalization and global competition, human aspiration, symbolism, and ego [10]. Certainly, cities around the globe are experiencing a tall building boom. Asia is clearly leading the way in this regard, with unprecedented tall building construction occurring in cities such as Shanghai, Beijing, Nanjing, Shenzhen, Guangzhou, Dalian, Wuxi, Hong Kong and Taipei (Greater China); Tokyo, Osaka and Nagoya (Japan); Bangkok, Pattaya and Nonthaburi (Thailand); Seoul, Busan and Incheon (South Korea); Kuala Lumpur (Malaysia); Jakarta (Indonesia); Makati, Quezon and Manila (Philippines); Mumbai (India) and Singapore, among others. Middle Eastern cities such as Dubai, Jeddah, Doha, Mecca, Tel Aviv, and Beirut also have been vigorously building tall. For example, Dubai has built the world’s tallest building, and Jeddah is building the next tallest. North American cities such as New York, Chicago, Miami, Los Angeles, San Francisco, Toronto, and Calgary are experiencing a renewed interest in building skyscrapers. South American cities (e.g., Santiago, Cartagena, Buenos Aires, and São Paulo) and Central American cities (e.g., Panama City, Mexico City, Monterrey, and Guadalajara) also are building more tall buildings. Even African cities such as Johannesburg, Pretoria, Sandton, Dar es Salaam, Nairobi, and Lagos are increasingly embracing the tall building typology [12,13]. 1.3. Critiques of Tall Building Developments Numerous scholars have pointed out serious concerns about tall buildings. For example, Ken Yeang, a leading figure on sustainable tall building developments, stated that, “At the outset, we should be clear that the skyscraper is not an ecological building type. In fact, it is one of the most un-ecological of all building types” (p. 84 [14]). He illustrates the notion of “unecologicalness” by arguing that tall buildings require excessive materials and sophisticated structural systems to build so that they are able to withstand greater wind forces that prevail at higher altitudes. They also demand greater energy to construct, operate, and maintain. Many of these problems stem from the vertical orientation of this building typology. Earlier, Christopher Alexander and colleagues in their seminal book A Pattern Language rejected the high-rise city altogether as a viable human habitat. They passionately explained their reasons (p. 114 [15]). Buildings 2018, 8, 7 3 of 31 Pattern 21: FOUR-STORY LIMIT. There is abundant evidence to show that high buildings make people crazy. Therefore, in any urban area, no matter how dense, keep the majority of buildings four stories high or less. It is possible that certain buildings should exceed this limit, but they should never be buildings for human habitation. Similarly, Léon Krier, a prominent proponent of the New Urbanism movement, explains in his book The Architecture of Community that buildings should have no more than five floors [16]. James Howard Kunstler, a widely respected figure in urban geography, argues that skyscrapers generate urban pathologies. They also demand lots of energy and are expensive to retrofit. Ergo, when oil peak and climate change prevail, skyscrapers will become irreparable relics [17]. Likewise, the Danish architect and urban designer Jan Gehl in Life Between Buildings (1971) [18] and Cities for People (2010) [19] critiqued high-rise cities and praised low-rise ones in various parts of the world for they emphasize the value of human scale and provide abundant opportunities for healthy social interaction. The well-known Jane Jacobs in The Death and Life of Great American Cities (1963) praised human scale environments that foster an active pedestrian life [20]. Also, Hans Blumenfeld in his influential work The Modern Metropolis (1971) denounced tall buildings because they damage the historic fabric of cities [20]. 1.4. Purpose of the Study Indeed, upon scanning the social science, architecture, and planning literatures we find a plethora of scholars who critique tall buildings. However, these views are scattered and do not follow any particular order or a conceptual framework. This paper intends to identify, collate, and consolidate fragmented concerns and critiques of tall building developments and presents them in an accessible manner. It aims to help architects and planners to attain higher levels of sustainable tall building developments by avoiding and addressing common “unsustainable” aspects. As such, this paper forms a knowledge base that is essential to learn and examine unsustainable practices in tall buildings. It offers a detailed “check list” of topics and issues that are important to the sustainability of tall building development.